We already have a check for riscv_shorten_memrefs in riscv_address_cost.
This adds the same check to riscv_rtx_costs. Making this work also
requires a change to riscv_compressed_lw_address_p to work before reload
by checking the offset and assuming any pseudo reg is OK. Testing shows
that this consistently gives small code size reductions.
Tested with riscv32-elf rv32imac/ilp32 and riscv64-linux rv64gc/lp64d
builds and checks and there were no regressions.
Committed.
gcc/
PR target/97417
* config/riscv/riscv.c (riscv_compressed_lw_address_p): Drop early
exit when !reload_completed. Only perform check for compressed reg
if reload_completed.
(riscv_rtx_costs): In MEM case, when optimizing for size and
shorten memrefs, if not compressible, then increase cost.
---
gcc/config/riscv/riscv.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/gcc/config/riscv/riscv.c b/gcc/config/riscv/riscv.c
index ff41795a031..7d274596ba3 100644
--- a/gcc/config/riscv/riscv.c
+++ b/gcc/config/riscv/riscv.c
@@ -891,17 +891,13 @@ riscv_compressed_lw_address_p (rtx x)
bool result = riscv_classify_address (&addr, x, GET_MODE (x),
reload_completed);
- /* Before reload, assuming all load/stores of valid addresses get compressed
- gives better code size than checking if the address is reg + small_offset
- early on. */
- if (result && !reload_completed)
- return true;
-
/* Return false if address is not compressed_reg + small_offset. */
if (!result
|| addr.type != ADDRESS_REG
- || (!riscv_compressed_reg_p (REGNO (addr.reg))
- && addr.reg != stack_pointer_rtx)
+ /* Before reload, assume all registers are OK. */
+ || (reload_completed
+ && !riscv_compressed_reg_p (REGNO (addr.reg))
+ && addr.reg != stack_pointer_rtx)
|| !riscv_compressed_lw_offset_p (addr.offset))
return false;
@@ -1708,6 +1704,13 @@ riscv_rtx_costs (rtx x, machine_mode mode, int
outer_code, int opno ATTRIBUTE_UN
instructions it needs. */
if ((cost = riscv_address_insns (XEXP (x, 0), mode, true)) > 0)
{
+ /* When optimizing for size, make uncompressible 32-bit addresses
+ more expensive so that compressible 32-bit addresses are
+ preferred. */
+ if (TARGET_RVC && !speed && riscv_mshorten_memrefs && mode == SImode
+ && !riscv_compressed_lw_address_p (XEXP (x, 0)))
+ cost++;
+
*total = COSTS_N_INSNS (cost + tune_param->memory_cost);
return true;
}
--
2.17.1
